**Core Concept**
Small cell carcinoma of the lung is a highly aggressive and responsive type of non-small cell lung cancer. It is characterized by its rapid growth rate and early metastasis, but it is also highly sensitive to chemotherapy.

**Why the Correct Answer is Right**
Small cell carcinoma of the lung is known to respond exceptionally well to chemotherapy due to its high rate of cell division and lack of differentiation. This makes it more susceptible to the cytotoxic effects of chemotherapeutic agents. The primary chemotherapeutic agents used in the treatment of small cell lung cancer include platinum-based drugs such as cisplatin and etoposide.

**Why Each Wrong Option is Incorrect**
**Option A**: Non-small cell lung cancer (NSCLC) is a broad category that includes several subtypes, such as adenocarcinoma and squamous cell carcinoma. While some subtypes of NSCLC may respond to chemotherapy, it is not as responsive as small cell carcinoma.
**Option B**: Adenocarcinoma is a subtype of NSCLC and is not as responsive to chemotherapy as small cell carcinoma.
**Option C**: Squamous cell carcinoma is another subtype of NSCLC and is not as responsive to chemotherapy as small cell carcinoma.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the responsiveness of lung cancer to chemotherapy can vary greatly depending on the specific subtype and the stage of the disease. Small cell carcinoma is generally considered to be the most responsive to chemotherapy, and it is often treated with a combination of chemotherapy and radiation therapy.

**Correct Answer:** C. Small cell carcinoma of the lung.